Effect of the in-plane/out-of-plane applied magnetic field on the magnetic response of symmetric epitaxial La2/3Ca1/3MnO3/YBa2Cu3O7−δ/La2/3Ca1/3MnO3 junctions

The anisotropic magnetic behavior of all oxide symmetric Ferromagnet (F)/Superconductor(S)/ Ferromagnet(F) [La2/3Ca1/3MnO3(F)/Y Ba2Cu3O7−δ(S)/La2/3Ca1/3MnO3(F)] heterostructures is reported. An external magnetic field was applied both parallel (in-plane, μ0H∥a-b-plane) and perpendicular (out-of-plane, μ0H∥c-axis) to the plane of the heterostructure. The magnetization hysteresis loops, recorded at 5 K (< superconducting transition temperature Tc∼40K), showed a clear central peak around of zero field when the magnetic field was applied perpendicular to the plane of the trilayer. In turn, by measuring the in-plane M-H dependence, the central peak disappeared. Contrarily, at temperatures T>Tc, the expected magnetic behavior of the ferromagnetic layer was detected independent of the direction of the applied magnetic field. Additionally, the active presence of the diamagnetic and ferromagnetic phases in the F/S/F heterostructure was corroborated by measuring the dependence M(T) under the zero field cooling (ZFC) and field cooling (FC) regimen. Whereas the in-plane ZFC and FC M-T dependences showed the typical behavior of the ferromagnetic component, the out-of-plane ZFC and FC M-T dependences displayed a conspicuous increase in M at ∼40 K. Such rise in M below Tc points out to the presence of a paramagnetic Meissner effect, which had been reported only for fields applied parallel to the surface of the films.